Fluid pressure switch



w 22, 1950 J. v. OLlVEAU 2,519,596

FLUID PRESSURE SWITCH Filed April l9, 1949 3 Sheets-Sheet 2 i. Tic}. 4.

27" INVENTOR. Jay/v K Gal 5M 15 2, 1950 J. v. OLIVEAU 2,519,596

FLUID PRESSURE SWITCH Filed A ril 19, 1949 s Sheets-Sheet 5 INVENTOR. /0///v flun /M Patented Aug. 22, 1950 FLUID PRESSURE SWITCH John V. Oliveau, Mineola, N. Y., assignor to The Acrotec Corporation, Greenwich, Conn., a cor poration of Connecticut Application April'19, 1949, Serial No. 88,351

19. Claims.

My invention relates to a fluid pressure control device and more particularly to a device of this type which is explosionprooi and which may be readily adjustable withoutthe necessity foropening it.

This invention is applicable to many different types of pressure control, such as differential pressures, subatmospheric pressures, etc.

In my present invention 1- provide a case to enclose the various elements, and more particularly the electric control switch and pressure actuated elements for operatingsame.

The pressure actuated elements are contained in a cylindrical shell closed at its ends and slidable axially in the case and having externally threaded end portions projecting a slight distance beyond the wall of the case. Threaded on these projecting ends are adjusting nuts preferably-of annular shape, there being one nut for each projecting end, so that b loosening one and tightening the other the shell may be adjusted longitudinally and locked in adjusted position. The shell isheld from rotational movement.

Mounted in the shell are one or more pressure controlled expansible elements, the expansion and contraction of which actuate an arm of the switch mounted in the case. Preferably the switch is acted upon by a small ball carried by an expansible element in a suitable mounting means and bearing directly on the switch arm.

The case is not leakprooi but has a slight clearance of, for example, one to a few thousandths of an inch, through which gases may-pass under pressure. If an explosive mixture should be formed within the case and become ignited by a spark from the switch, the pressure developed will expel the products of explosion through the very fine passages provided so that they will escape gradually until the pressure is relieved and, through this gradual passage be cooled to normal temperature, or temperature of the case and, therefore, be unable to ignite anyexplosive mixture about the control mechanism or ignite or set fire to any combustible materials.

The various features of the invention are illustrated by way of example in the accompanying drawings in which Fig. 1 is a view in elevation. of an explosionproof control mechanism embodying a preferred form. of the invention;

Fig. 2 is a plan section of the mechanism taken on line 22 of Fig.1;

Fig. 3 is a detail section on a somewhat larger scale taken on line 33 of Fig. 2;

Fig. 4. is a plan view of the control mechanism shown inFig. 1;

(Cl. ZOO-$1.5)

Fig. 5 is a vertical section taken on the line 5-5 of Fig. 4;

Figs. 6, 7 and 8 are diagrammatic illustrations of modified forms of the control apparatus.

Referringmore particularly to the accompanying drawings, the moving elements of the mechanism are enclosed in a case I0 having suitable lugs H secured to a mounting member and having an electric switch l2 mounted on a supporting base [3 on the inner surface of the case wall, as shown in Figs. 2 and. 3.

The switch I2 is actuated by a lever pivoted at [3 on a bracket of the switch l2 and having an actuating arm l4 extending sidewiseinto a cylin drical shell l5 extending vertically through the opposite upper and lower walls l6 and l! of the case and having an opening 18 through which the arm I 4 passes.

The shell [5 is provided with a longitudinalslot H], as shown in- Figs. 2 and 3, into which projects the studs of a pair of screws 20 mounted in the vertical wall of the case and covered by a plate 21. The engagement of the studs of thescrews 2B in the slot 19 permits the shell [5 to move longitudinallyor axially in the case but prevents its rotational movement.

The ends of the shell l5 projecting through: the walls l5 and I! are externally threaded as at 22 and 23 and on these externally threaded portions are screwed adjusting nuts 24- and 25.

It will be apparent that by loosening one of these nuts and tightening the other the shell may be adjusted longitudinally without opening the case.

The ends of the shell are closed by-plugs 26; on which are mounted one or more expansible elements, two such elements 27 and 28, in opposed aligned position, being shown byway of illustration in Figs. 1 and 5. Communication to the interior of these expansible elements is obtained by passages through the plugs 26', ending in connecting'projections 2? and 28. The free endsof the expansible elements are connected'by a connecting bridge piece 29, the position of which is dependent upon relative pressures in thej expansible elements 2 and 2,8.

Movements by the bridge piece 29 are transmitted to the switch arm M by meansof a bearing ball 30 contained in a recess in the yoke 29, which is closed partly about the ball to retain it inposition.

It will be apparent, therefore, thattheposition of the switch l2 will depend upon the position of the yoke 29 and ball 30 governed by the relative pressures or differences in pressures in the; expansible elements 21 and 28. The differences in pressure required to operate the switch arm M or to move it to a predetermined position may be adjusted by shifting the shell I5 longitudinally in one direction or the other by a, suitable adjustment of the positioning nuts 24 and 25. And it is obvious that this adjustment may be made from the outside of the case and without opening or disturbing any of the parts. In order to prevent excessive movement of the expansible elements such as might result in their rupture, the projections or nipples are extended inwardly Within the expansible elements as at 3| and 32.

In using a control device of the above type where combustible materials or gases are involved, there is always the possibility of an explosive mixture being formed within the case and about the control switch, as a spark may be formed by the opening of the switch elements and an explosion may arise within the case generating a high pressure.

In the present invention these explosive gases are permitted to escape through narrow passages in which they are rapidly chilled to the temperature of the case before escaping and, therefore,

closing the shell as, for example, at the pointsindicated at 53, 3c, 35 and 36, and also between other fittings on the case such, for example, as

between the surfaces of an outlet fixture 31 for '7 and 8. In Fig. 6 there is illustrated a switch which is altitude compensated, having a pressure bellows 2? which is opposed by an altitude bellows 28. The latter is evacuated and is provided with a spring i i. The atmospheric pressure acting on bellows 2'? is balanced by the atmospheric pressure on bellows 28 so that the switch is actuated by the absolute pressure, the difierences in atmospheric pressure at various altitudes being compensated. The bellows 28 is supported on an adjustable supporting stem 45.

In the embodiment shown'in Fig. 7 the expansible element may be replaced by a spring 48 mounted on a supporting plate 37 supported by an adjusting screw it so that the expansible element 2'! will operate solely against the spring 46. In this case the apparatus would be used as a straight gauge pressure switch.

A switch of the above type may be connected by means of a capillary tube and a temperature sensing bulb filled with a low boiling point liquid in which case the switch may be used as a temperature actuated switch. The sensing tube could be placed at a position remote from the switch.

In the embodiment shown in Fig. 8 a single bellows 2'! is employed together with a spring 49 contained within the bellows. The bellows or expansible element 2'! may then be evacuated so that it will expand when the pressure of the surrounding atmosphere decreases as, for example,

withincrease in altitude so that theswitch will operate when a predetermined altitude is reached. It may also be supported by an adjusting screw 50.

Through the above invention I have, therefore, provided an explosion-proof pressure actuated switch, the point of actuation of which may be adjusted readily from the exterior of an enclosing casing and without removing or opening any of the parts.

Having described my invention, what I claim 1. Fluid pressure control device which comprises a case, a cylindrical shell extending through said case and projecting through opposite walls thereof, said shell being movable axially but retained from rotation in said case, the projecting portions of said shell being externally threaded, the ends of said shell being closed, positioning nuts one threaded on each projecting portion of said shell to abut the wall of said case, an expansible element in said shell and an electric switch in said case outside of said shell and having an operating arm engaging said expansible element.

2. The control device of claim 1 in which said shell has a small clearance with the walls of said case to permit the escape of gases under pressure.

3. The control device of claim 1 in which said case is provided with escape passages of small clearance to permit the escape of gases under pressure.

4. The control device of claim 1 in which a bearing ball is mounted on said expansible element to bear against the arm of said switch.

5. The control device of claim 1 having a pin and groove connection between said shell and said case to prevent rotation of said shell in said case.

6. Fluid pressure control device which comprises a case, a cylindrical shell extending through said case and projecting through op- [posite walls thereof, said shell being movable axially but retained from rotation in said case, the projecting portions of said shell being externally threaded, the ends of said shell being closed, positioning nuts one threaded on each projecting portion of said shell to abut the wall of said case, a pair of opposed expansible elements in said shell, a connecting bridge piece between the opposed free ends of said expansible elements and an electric switch in said case outside of said shell having an operating arm engaged by said connecting bridge piece.

'7. The control device of claim 6 in which a bearing ball is mounted on said bridge piece to bear against the arm of said switch.

8. The control device of claim 7 in which a spring is provided to bear against one of said expansible elements.

9. The control device of-claim l in which a spring is mounted to oppose said expansible element.

10. The control device of claim 1 in which a spring is mounted Within and acting to expand said expansible element. a L

JOI-IN V. OLIVEAU.

REFERENCES CKTED The following references are of record in the file of this patent:

UNITED STATES PATENTS,

Number Name Date 1,932,988 Raney Oct. 31, 1933 2,376,14 4 Levine May 15, 1945 

